In the core public administration classification system, Treasury Board (“TB”) refers to the organization of work and employees as the occupational group structure. The occupational group is a series of jobs or occupations related in broad terms by the nature of the functions performed.

Occupational groups are designated by a two-letter abbreviation that is shorthand for the occupational group's title. For example, there are six LP levels: LP-00 (Articling students), LP-01, LP-02, LP-03, LP-04 and LP-05. The number assigned to the occupational group designator refers to the level within the group.